For example, in a production line of an optical disc apparatus and an electronic device having an angular velocity detecting function, an industrial robot is used in an inspection process for evaluating functionalities of the produced device. Typically, the robot includes a workbench on which devices to be inspected (hereinafter also referred to as work pieces) are mounted, a transfer robot for transferring the work pieces to the workbench, an inspection unit for inspecting the work pieces mounted on the workbench, and the like.
This sort of the transfer robot includes clamp units for holding the work pieces. For example, Japanese Patent Application Laid-open No. 2009-241168 discloses a component holding apparatus including three or more holding claws for holding components, and mutually independent driving sources for driving the holding claws.
Patent Document 1: Japanese Patent Application Laid-open No. 2009-241168